<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    
    <button>按钮</button>

    <script>
        let btn = document.querySelector('button');

        function fn(){
            console.log(this);
        }

        let obj = {
            fn: function(){
                console.log(this);
            }
        }

        //创建一个新函数  bind 用来改变this的值, 返回新函数, 
        let newFn = fn.bind(obj);

        // let fn = () => {
        //     console.log(this);
        // }

        // btn.onclick = function(){
        //     console.log(this);
        // }

        btn.onclick = newFn;
        // btn.onclick = obj.fn;

    </script>
</body>
</html>